Fire finding switch



N0v.25,1947. ,F,ALLAHAN n 2,431,443

FIRE FINDING SWITCH Filed June 2e, 19147 2 sheets-sheet 1 To suf/ML C. F. CALLAHAN FIRE FINDING swiTcH Filed June 26, 1947 Nov. 25, 194,7.

2 Sheets-Sheet 2 CVPLLS' FPfDfR/CK (ALLAH/1N Patented Nov. 25, 1947 UNITED STATES PATENT FFICE 4 Claims.

This invention relates to means and methods i for detecting the presence and pointing out the location of lires shortly after their inception, and before they have progressed beyond control.

This application is a continuation-in-part of my co-pending application, Serial No. 727,659, led February 10, 1947.

It particularly relates to an instrument which in response to heat closes an energized circuit which includes a warning signal, in which closure of the circuit and persistence of the signal is maintained after the instrument is partially destroyed by the fire, and until it is completely destroyed, and in which the construction of the instrument is such that its destruction by excessive heat is materially delayed.

It is a matter of public knowledge that for the past few years loss of both life and property as a result of fires has increased in the United States of America. The reason for designating the instrument hereinafter described as a fire finding switch is due to the fact that res originating fn hotel rooms, apartment buildings, department stores, and many other places, are undiscovered in many instances until extensive property loss, and perhaps loss of life has already occurred. The fire departments over the country, as disclosed by the public press, experience great difficulty and lose valuable time in locating the exact spot or origin of fire.

This invention furnishes a means and method of detecting the presence of fires and pointing out the location of res shortly after their inception, and before they have progressed beyond control. Means for detecting and indicating the location of lires in individual rooms of hotels or other places such as apartment buildings and oiiice buildings have been in the past, and are now, totally inadequate to meet the emergency. Fire departments in their unending battle against property loss and the loss-of life by fires are each day forced; rst, to overcome the handicap of delay in fighting fires due to lack of knowledge that a fire exists; and second, due to the lack of information as to the exact location of a fire in a building. The device hereinafter described is capable of pointing out immediately the exact room of a hotel or other building in which re of unwarranted character exists.

This device may be connected directly with the telephone in any ordinary hotel room, hospital room, or room or space in any other building, and by this simple means communicate with the operator at the switchboard in said building by flashing a light and sounding a signal notifying the operator or attendant at said switchboard that unwarranted heat, probably a re, exists in a certain room or place guarded by this instrument. If this device is connected with the telephone in a hotel room, or space in any other (Cl. 20G-441) building, the simplicity and economy of guarding against re by this method would result in a saving of both life and property throughout the country at a nominal cost.

This invention may also be connected with its own central station energized by electrical power within said station and its leads or wires from said station may spread out from this central point so as to guard any and every danger spot within a structure, whether it be a hospital, hotel, department store, private home, warehouse, ship, or other place. Each pair of lead wires connected with this device and a central station is capable of flashing a light and sounding a signal at its central station notifying the operator or attendant at said station that unwarranted heat, probably a fire, exists at a certain location guarded by said instrument.

To illustrate, Room 777 stencilled or stamped on or over a room door of a hotel or other building is understood to signify that this room is located on the seventh floor of said building and that the room itself is number 777. Therefore, the number 777 stencilled or stamped either over or under a light signal on a central switchboard connected with a central station in said building signifies instantly to the operator or attendant that unwarranted heat, probably a re, is present in Room 777, on the seventh floor of said building, for the operator or attendant both know that Room 777 is connected with light signal number 7 77 at said central station or switchboard and also connected with the fire-finder attached to the inside wall of Room 777 in said building.:

The objects of the present invention are:

To provide means to indicate the existence and location of a re at an early stage in its development, in order that steps 'may be taken to stop the re before it reaches a dangerous stage or spreads uncontrollably;

To provide a heat responsive instrument adapted to close an alarm circuit on a very minor rise of temperature, in which the switch closure is maintained after the device may have been partially destroyed by the heat to insure that an alarm signal in the circuit will continue and persist until the instrument is destroyed;

To 'provide a heat responsive circuit closing thermo-bulb and tube in which destruction of the bulb is delayed over a substantial period of time and during such time the alarm circuit is lmaintained closed and the signal persists after destruction of the bulb and until the tube is dev stroyed;

To provide a heat responsive circuit closing switch of thermometer type in which destruction ofthe bulb will not cause evacuation of the mercury from the thermometer tube above such bulb and a signal in the circuit will persist.

The means by which the foregoing and other' objects are accomplished and the method of their accomplishment will readily be understood from the following specication on reference tothe accompanying drawings, in which:

Fig. 1 is a sectional front view of the instrument taken on the center line of the mercury column thereof showing circuit contacts open.

Fig. 2 is a sectional side elevational view taken on the center line of the column after the bulb thereof has been destroyed by excessive heat, showing the circuit contacts closed.

Fig. 3 is a rear view.

Fig. 4 is a front elevational view.

Fig. 5 is a sectional plan view taken on the line V-V of Fig. 1.

Fig. 6 is a face View of a signal board mounted on a desk.

Fig. '7 is an enlarged View of the signalboard oi Fig. 6, partially broken away, and diagrammatically of a typical circuit.

Referring now to the drawings in which the va-rious parts are indicated by numerals:

'Ihe nre-finder includes a heat responsive instrument of thermometer type, which comprises a vertically disposed tube I2 having at its lower end a bulb I4, preferably cylindrical, and at its upper end a reservoir IS, the walls of the reservoir I6 being of deiinitely greater thickness than the walls of the bulb I4, and inherently less susceptible to destruction by expansion than are the walls ofthe bulb I-4. The bore I2A of the tube I2 is extremely minute and the wallsof the tube heavy, whereby its destruction by excessive heat is remote.

The bulb I4 is filled with mercury I8, which, responsive to a rise in temperature, expands upward through the bore IZA and into the reservoir I6` at the top. The instrument is hermetically sealed and substantially all of the air is exhausted from the reservoir and any other unfilled portions of the instrument to establish as nearlyl as possible an absolute vacuum therein. I

Contacts 2l) and 22, as of wire, intermediate the height of the tube and definitely below the reservoir I 6 and above the bulb I4, extend through the walls of the tube I2 to the bore I2A and into contact in the bore with the-thread of mercuryl forced upward by expansion of the mercury I8 of the bulb due to heat. Preferably sufficient mercury is used to lill the tube above the lower contact 20, but not to the level of the upper contact 22, at normal room temperature. Exteriorly of the tube the contacts 20 and 22 intimately engage correspondingly spaced metallic rings 24V and 26 which surround the tube.

The thermometer is supported by metal clips 28- and 3U: which are spaced apart to conform to the-spacing of the rings 24, 2B and make electrical contact with the rings. The tube may be additicnally supported by clips 32 and 34. The clips are mounted on a block or strip 36 of dielectric, heat-resistant material as Bakelitej which in turnv may be carried by a base 38, preferably of sheet metal.

The clips are secured to the baseby threaded shanlrs lil and nuts 42. The nuts of the clips 28 and 3D also secure circuit leads 44 and 4B respectively to the clip 33 and Contact 2D, and to the clip 3Q and contact 22. Dielectric blocksl 48 electrically insulate the nuts, threadedk shanks and leads from the base. The front of the thermometer is preferably protected by a shield 5U having openings from time to time therethrough, secured at its upper and lower ends to thev base 38'.

Preferably the lower end of the base has downwardly converging side portions 38A narrowing the base at its lower end and reducing its area in the vicinity of the bulb and its heat retarding effect thereon, and the shield is cut away as much as possible to yet afford bulb protection.

Figs. 6 and 7 illustrate the manner in which the device may be set up for use.

In these figures, 52 is a cabinet conveniently mounted as on a desk 54. On the face of the cabinets are light bulbs I20, I2|, etc., designated by corresponding numbers on the cabinet face in adjacency to the bulb, each of which numbers corresponds to the number of a room, as the room I20, in which the-.heat responsive instrument which is in circuit therewith is placed.

The circuits are energized, as by a power circuit 56 through a transformer 58, from which leads G0 and 62 extend. One lead, as the leady 6U, is connected through an audible signal 64 and lead 66V to a bus B8, branch buses 10, and individual leads 12 to the individual bulbs as the bulb |20. From the transformer the lead 62 extends into adjacency to the rooms, and is connected through individual leads to the heat-responsive instrument in the rooms, as through the lead 46, to the contact 22 of the instrument in the room |20 shown. From the opposite contact 2D of the instrument the lead 44 returns to the light I ZIlcompleting a circuit normally open only at the contacts 20-22 at ordinary room temperatures. Between the room and the lights, the lead 44 is shown enclosed with other leads 'I4 in main and branch cables or conduits 16, 18.

For use, the instrument is supported on a wall of a numbered room, usually near the ceiling, and a circuit established from the contacts 20, 22 to the signal numbered to correspond to the room number.

Should a fire start in the room, raising the temperature, the expansion of the mercury bridges the contacts and sets up the signals, and the signals persist so long as the instrument remains intact. Subsequent to bridging of the contacts the mercury overflows into the reservoir I6 and this chamber being under vacuum, no resisting pressure is set up until the reservoir is completely filled, the vacuum thus materially delaying the establishment of the destructive pressures and extending the period of signal persistence.

Should the fire be a smoldering one and the temperature rise show, this may give ample time to observe on the signal board the location of the fire. Should, however, the fire be of the even more dangerous flash type, the instrument bulb may be blown off before check of the board for room location can be made and fatal delay occur in finding where the fire is.

In the present instrument, however, the destruction of the bulb allows atmospheric air pressure to resist the escape of the mercury from the tube and the mercury being under no pressure except its own weight is held', at least in the tube, by this air pressure, capillary attraction and frictional resistance, until the fire completes the destruction of the instrument and ample time is given.

It will particularly be noted that the wall' of the reservoir is heavier than the wall of thei bulb so that destruction of the bulb will occur rst and that the reservoir is smaller than the bulb to further insure this result.

Attention is also called to the cylindrical shape of the bulb insuringv more rapid initial response to thev re and to the filling of the tube into adjacency to the upper contact under o-rdinary room temperature for the same purpose.

It will, however, be distinctly understood that these features and their reiteration here shall not be construed to limit any claim herein in which they are not specifically set out.

I claim:

1. A heat responsive circuit control instrument including, an elongate vertically disposed tubular body having a relatively small and completely free and unobstructed capillary bore of substantially uniform diameter extending throughout the length thereof, a bulb carried by the lower end of said body and a reservoir carried by the upper end thereof each communicating with said bore, a pair of vertically disposed and spaced contacts leading into the bore of said tubular body intermediate its ends and each respectively being formed for connection to a source of electric energy, and mercury lling said bulb and a portion of the bore of the tubular body to a point at least below the upper of said contacts and responsive to a predetermined degree oi temperature for bridging said contacts, said instrument being hermetically sealed and said reservoir and other unfilled portions of said bore being evacuated so as to establish and maintain a vacuum therein, whereby positive bridging of the contacts by the mercury in response to a predetermined degree of temperature will persist and be maintained constant by said vacuum even in the event of subsequent rupture of the bulb by an increase in temperature above said predetermined degree.

2. A heat responsive circuit control instrument including, a vertically disposed elongate tubular body having a relatively small and completely free and unobstructed capillary bore of substantially uniform diameter extending throughout the length thereof, a bulb carried by the lower end of said body and a reservoir carried by the upper end thereof each communicating with said bore, the walls dening the capillary bore and reservoir being of relatively greater thickness than the wall defining said bulb so that the wall defining the bore and reservoir will withstand greater heat and pressure than the wall defining the bulb, spaced opposed contacts leading into the bore of said tubular body intermediate the ends of the latter and each respectively being formed for connection to a source of electric energy, and an electrically conductive liquid filling said bulb and bore to a point slightly below said contacts and responsive to a predetermined degree of temperature for bridging said contacts, the reservoir and uniilled portion of the bore being evacuated and hermetically sealed so as to establish and maintain a vacuum therein above said electrically conductive liquid, whereby positive bridging of the contacts by said liquid in response to a predetermined degree of temperature will persist and be maintained constant by said vacuum even in the event of subsequent rupture of the bulb by an increase in temperature above said predetermined degree.

3. A heat responsive circuit control instrument including, a vertically disposed elongate tubular body having a relatively small and completely free and unobstructed capillary bore of substantially uniform diameter extending throughout the length thereof, a bulb carried by the lOWer end of said body and a reservoir carried by the upper end thereof, each having communication with said bore, the walls defining the capillary bore and reservoir being of relatively greater thickness than the wall defining said bulb so that the walls deiining the bore and reservoir will withstand greater heat and pressure than the walls defining the bulb, a pair of vertically disposed and spaced contacts leading into the bore of said tubular body intermediate its ends and each respectively being formed for operative connection to a source of electric energy, and mercury filling said bulb and a portion of the bore of the tubular body to a point spaced slightly below the upper contact and responsive to a predetermined degree of temperature for bridging said contacts, said instrument being hermetically sealed and said reservoir and unfilled portion of said bore being evacuated so as to establish and maintain a vacuum therein, whereby positive bridging of the contacts by thel mercury in response to a predetermined degree of temperature will persist and be maintained constant by said vacuum even in the event of subsequent rupture of the bulb by an increase in temperature above said predetermined degree.

4. A heat responsive circuit control instrument including, a vertically disposed elongate tubular body having a relatively small and completely free and unobstructed capillary bore of substantially uniform diameter extending throughout the length thereof, a bulb carried by the lower end of said body and reservoir carried by the upper end thereof, each having communication with said bore, the walls defining the capillary bore and ieservoir being of relatively greater thickness than the wall defining said bulb so that the walls defining the bore and reservoir will withstand greater heat and pressure than the wall delining the bulb, a pair of spaced contacts leading into the bore of said tubular body intermediate its ends and each respectively being formed for operative connection to a source of electric energy, and mercury filling said bulb and a portion of the bore of the tubular body to a point below said contacts and responsive to a predetermined degree of temperature for bridging said contacts, said instrument being hermetically sealed and said reservoir and the unfilled portion of said bore being evacuated so as to establish and maintain a vacuum therein, whereby positive bridging of the contacts by the mercury in response to a predetermined degree of temperature will persist and be maintained constant by said vacuum even in the event of subsequent rupture of the bulb by an increase in temperature above said predetermined degree.

CHARLES FREDERICK CALLAHAN.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS N umber Name Date 105,273 Sternberg July 12, 1870 626,124 Yankauer May 30, 1899 1,596,964 Goodhue Aug. 24, 1926 1,942,517 Noyes Jan. 9, 1934 2,003,956 Ronci June 4, 1935 

